我国公路钢桥结构的可靠度校准分析

对公路钢桥结构的作用和抗力进行了统计分析并基于现行公路钢桥规范对其进行了可靠度校准.通过误差分析和现场实测得出了恒载效应的概率分布和统计参数,其中分别考虑了沥青混凝土和水泥混凝土桥面铺装层自重的不同影响.抗力分析中分别就材料性能不定性、材料及构件几何尺寸不定性和结构计算模式不定性进行了计算,从而得出了我国常用的两种桥梁用钢的抗力统计参数.按照现行规范,分别考虑不同作用效应组合、不同汽车运行状态和活载服从不同概率分布类型的情况下,采用JC法对轴拉、轴压、偏心受压、受弯和受剪等5种构件进行了可靠指标校准.最后经综合分析得出了各级结构在脆性破坏和延性破坏下的目标可靠指标建议值.

Calibration analysis of reliability of steel highway bridges in China

A calibration analysis based on reliability principles has been developed for steel highway bridges in China because the Chinese current specification for steel highway bridge still employs the allowable stress design methodology.The study includes three parts,i.e.stochastic analyses of loads and resistances and the calibration of the reliability index respectively.The probabilistic distribution and statistical parameters of steel members'gravity are derived from error estimation and investigation on-site across China.The data of car loads are collected from 4 provinces.The probabilistic distribution and statistical parameters of the resistance is obtained from three aspects.The first is uncertainty analysis of materials properties;the second is geometric parameters uncertainty;and the third is model's calculation uncertainty.Two major bridge constructing steels are considered.Then according to the current specification,the first-order secondary-moment method(JC method)is used to calibrate the reliability indexes of five typical members which are axial tension member,axial compression member,eccentric compression member,beams and shear member.Thus,eight groups of reliability indexes are obtained which are of bridges subjected to different loads combinations when car loads effect belongs to extreme value typeⅠdistribution and normal distribution respectively.So the recommended reliability indices of members subjected to plastic and brittle failure which belong to different safety grades are calculated respectively.